I had a papillary/follicular mix cancer. I had my thyroid removed in July and had RAI last month. I saw a Radiation oncologist for this treatment. From what I understand, it is almost always necessary to have rai with thyroid cancer to make sure ALL of your thyroid cells are gone. I have heard of some people who didn't need this because their tumors were very small and their surgeons were able to get all of their thyroid, but this is rare.
I'm not sure why they're having you see an oncologist and a radiologist. I would think they will probably work together in deciding about your RAI. I would ask questions like:
~if you'll have to stay in isolation and how long
~precautions you will need to take once you're home(including how long to stay away from kids)
~ask about the low iodine diet
~ask about when you will have your body scans
~if you're on meds, you'll need to know when to stop taking them (and when you can start them again after treatment)
I'm sure there is more you'll want to ask, but this is all I can think of right now.